Data Over Cable Service Interface Specification (DOCSIS) is a telecommunications standard that enables high-speed data transfer over cable television (CATV) systems. DOCSIS is employed by cable television operators to provide data, including Internet and voice data, over a hybrid fiber-coaxial (HFC) infrastructure.
Within the HFC infrastructure, traffic (e.g., data packets) can be classified into separate DOCSIS service flows (SF). These service flows may be used to meet accounting, regulatory, QoS (Quality of Service), and other requirements.
More generally, a SF is a virtual construct between a Cable Modem Termination System (CMTS) and a CM (Cable Modem) for separating traffic from the same CM into different classifications. As such, each classification is statically defined and stored in each CM. Further, each SF can be associated with one or more classifications. The classifications are typically defined as a range of source/destination IP (Internet Protocol) blocks. For example, if IP video traffic is sent to, and received from, the 10.10.10/24 network block, then this signature can be used as a classification for a video service flow.
Unfortunately, the number of available classifications for service flows is limited to no more than 32 in most DOCSIS implementations.